Crucial fix: Ensure agent code is copied over properly

Author: klieret

codeclash/games/game.py

@@ -200,7 +200,14 @@ def get_metadata(self) -> dict:
     def _pre_round_setup(self, agents: list[Player]):
         """Copy agent codebases into game's container"""
         for agent in agents:
+            # First make sure that the folder in the game container is removed
+            # This is important for 2 reasons:
+            # 1. Subtle differences in docker cp behavior regarding to trailing slashes
+            #    depending on whether the destination exists
+            # 2. If files are removed from the agent container, they should also be removed
+            #    from the game container
             self.logger.debug(f"Copying {agent.name}'s codebase")
+            assert_zero_exit_code(self.environment.execute(f"rm -rf /{agent.name}"), logger=self.logger)
             copy_between_containers(
                 src_container=agent.environment,
                 dest_container=self.environment,

codeclash/utils/environment.py

@@ -23,7 +23,11 @@ def copy_between_containers(
 ):
     """
     Copy files from one Docker container to another via a temporary local directory.
+
+    Be extremely careful with trailing slashes in src_path and dest_path, the behavior
+    of docker cp is also different depending on whether the destination exists.
     """
+    print(f"Copy between containers: {src_path} -> {dest_path}")
     with tempfile.TemporaryDirectory() as temp_dir:
         temp_path = Path(temp_dir) / Path(src_path).name
 
@@ -66,6 +70,9 @@ def copy_to_container(
     Copy a file or directory from the local filesystem to a Docker container.
 
     The copy operation is recursive for directories.
+
+    Be extremely careful with trailing slashes in src_path and dest_path, the behavior
+    of docker cp is also different depending on whether the destination exists.
     """
     if not str(dest_path).startswith("/"):
         # If not an absolute path, assume relative to container's cwd
@@ -76,6 +83,7 @@ def copy_to_container(
         str(src_path),
         f"{container.container_id}:{dest_path}",
     ]
+    print(f"Copy to container: cmd={cmd}")
     # Ensure destination folder exists
     assert_zero_exit_code(container.execute(f"mkdir -p {Path(dest_path).parent}"))
     result = subprocess.run(cmd, check=False, capture_output=True, text=True)
@@ -95,13 +103,17 @@ def copy_from_container(
     Copy a file or directory from a Docker container to the local filesystem.
 
     The copy operation is recursive for directories.
+
+    Be extremely careful with trailing slashes in src_path and dest_path, the behavior
+    of docker cp is also different depending on whether the destination exists.
     """
     cmd = [
         "docker",
         "cp",
         f"{container.container_id}:{src_path}",
         str(dest_path),
     ]
+    print(f"Copy from container: cmd={cmd}")
     Path(dest_path).parent.mkdir(parents=True, exist_ok=True)
     result = subprocess.run(cmd, check=False, capture_output=True, text=True)
     if result.returncode != 0: